Thermodynamics From First Principles: Prediction Of Phase Diagrams And Materials Properties Using Density Functional Theory

First principles calculations have become one of the main computational methods in condensed matter physics and physical chemistry due to their high degree of accuracy without the usage of any fitting parameters. Interest has been growing in the engineering disciplines to exploit these properties to predict new materials with desired material properties, greatly accelerating the prototyping of materials over experimental methods with a degree of accuracy not found in other computational methods. In this thesis, first principles calculations will be applied to understand material properties of four classes of chemical systems with promising mechanical or thermodynamic applications, but whose experimental characterizations are either incomplete or questionable: boron carbide, molybdenum-niobium-tantalum-tungsten, copper-palladium-sulfur, and various early-late transition metal alloys. For all classes, the phase stability will be examined, of particular interest B-C and Mo-Nb-Ta-W due to the controversy surrounding the phase diagram of the former and the interesting “high-entropy alloy” behavior of the later. In addition, for Cu-Pd-S, various thermodynamic quantities associated with resistance to sulfur poisoning will be calculated, and for the early-late transition metal alloys, the elasticity will be examined, with attention paid towards possible transferability to the field of amorphous materials. All four of these disparate systems show overall semi-quantitative agreement with known experimental results, highlighting the versatility of first principles calculations.